1. Field of the Invention
The present invention relates to a tray for integrated circuits, particularly those of the ball grid array (BGA) type. The tray is stackable and includes an upper side and a lower side, wherein the upper and lower sides of each tray have storage pocket areas that align with one another when trays are stacked. More particularly, both upper and lower sides of the trays include support elements forming ledges of equal uniform height to restrain and stabilize the integrated circuit chip in the Z-direction (perpendicular to the floor) and ridges restrain and stabilize the integrated circuit chip in the X-Y direction (parallel to the floor). The ridges on one side of the tray stabilize a first pair of diagonally opposed corners of the integrated circuit chip while ridges on the other side of an adjacent tray stabilize a second pair of diagonally opposed corners of the integrated circuit chip.
2. Description of the Prior Art
In the prior art, it is known to use stackable trays for the storage and transportation of integrated circuits, particularly ball grid array (BGA) integrated circuits. These stackable trays typically form discrete storage pockets for engaging individual chips. Moreover, these trays are sometimes used as a carrier to position the chips for inspection and automated assembly apparatus. Inspection usually requires that the balls face upward whereas assembly generally requires that the balls face downward. Therefore, it is important that the integrated chips are stabilized in the X-Y directions whether the chips are in a tray that is in the right side up or upside down configuration. That is, the trays should be “flippable” or capable of supporting chips in either orientation.
Moreover, it is imperative that these trays provide substantial mechanical and electrostatic/electromagnetic protection for the chips.
Some examples of the prior art stackable trays can be found in U.S. Pat. No. 5,400,904 entitled “Tray for Ball Terminal Integrated Circuits”, issued to Maston et al. on Mar. 28, 1995; U.S. Pat. No. 5,103,976 entitled “Tray for Integrated Circuits with Supporting Ribs”, issued to Murphy on Apr. 14, 1992; U.S. Pat. No. 5,080,228 entitled “Integral Carrier and System for Electrical Components”, issued to Maston et al. on Jan. 14, 1992; U.S. Pat. No. 5,000,697 entitled “Carrier System for PGA Electrical Components”, issued to Murphy on Mar. 19, 1991; U.S. Pat. No. 4,765,471 entitled “Electrical Component Carrier”, issued to Murphy on Aug. 23, 1988.
An additional example can be found in commonly owned U.S. patent application Ser. No. 10/414,617, filed on Apr. 16, 2003 entitled “Stackable Tray for Integrated Circuits with Corner Support Elements and Lateral Support Elements Forming Matrix Tray Capture System”.